1. Field of the Invention
The present invention relates to a ternary pulse generation circuit in which the through current of a switching element is suppressed in order to reduce power consumption.
2. Description of Related Art
Solid state imaging devices are devices which comprise a photoelectric conversion section and a charge transfer section for transferring an information charge generated by the photoelectric conversion section in accordance with incident light to the charge transfer section, and which thereby obtain image data. Examples of solid-state imaging devices include CCDs (Charge Coupled Device) or the like.
A frame transfer type CCD solid-state imaging device, for example, includes an imaging section which functions both as a photoelectric conversion element and a vertical shift register, a storage section including a vertical shift register for temporarily buffering an information charge transferred from the imaging section, a horizontal transfer section having a horizontal shift register for transferring the information charge corresponding to one line sequentially output from the storage section, and an output section for outputting a voltage in accordance with the information charge output bit by bit from the horizontal transfer section. During image capturing using such a frame transfer type CCD solid-state imaging device, an information charge corresponding to the intensity of incident light is generated for each bit of the photoelectric conversion elements disposed in a matrix in the imaging section. Further, at the time of frame transfer, the information charge generated by each bit of the imaging section corresponding to one frame is vertically transferred by the vertical shift register and buffered in the storage section, and the information charge buffered in the storage section corresponding to one line is sequentially transferred to the horizontal transfer section.
In the solid-state imaging device, in order to increase the storage capacity for the information charge at the time of image capturing and the transfer efficiency for the information charge at the time of vertical transfer, it is necessary to control a clock pulse having different voltage values for image capturing and vertical transfer with a ternary clock pulse to be applied to the imaging section and the storage section.